Depending on where in the world there are typically 2 mitigation techniques to limit channel hogging, in EU we apply a duty cycle limit typically 0.1%, 1% or 10% depending on channel - we use the 10% DC channel for Downlinks so GW’s dont run out of capacity too easily. In other areas like US (I suspect for AU?) with US915 (AU915) there is a dwell time limit - a Tx can only stay on one channel for a max period - 400mS in US before having to frequency hop to another channel to start next Tx or continue. In some regions this might also be augmented/further constrained by requirements for LBT implementation in addition. That is one of the reasons why US (& I think AU) have more channels available (64) to allow for that hopping activity, where we simply limit based on DC. A typical GPS Sensor Payload might stay on air for ~1400-1800ms in EU at SF 12 but then can t TX again until DC time lapsed to allow next TX, where in US they cant use SF12 as that woudl break dwell time limit. As you say where the S/DCPF’s constrained on ferquency they quickly run out of capacity and artificially constrain ability to send Downlinks (disruptive to network operation as NS has no way to know it is sending through a crippled device and assumes the capabilities of a fully capable 8 channel GW) though as cslora pointed a correctly set up and programmed device could/should be agile enough to switch channels as needed once dwell time limit reached … in practice this rarely happens.
Believe this is all covered by the RED/EN regs in EU, FCC (part 15) in US, there are equivalents from ICC for Canada and others around the world - cant remember the AU regs/authority 